Motion-compelling mechanism for a hand tool



G. J. FlLlA 3, 7

MOTION-COMPELLING MECHANISM FOR A HAND TOOL Oct. 11, 1966 Filed May 6,1965 2 Sheets-Sheet 1 grwe/wtoo 650265 J. F/L/A 3% MWw ak ATTORNEY Oct.11, 1966 G. .1. FlLlA MOTION-COMPELLING MECHANISM FOR A HAND TOOL 2Sheets-Sheet 2 GEORGE d F/L/A ,J W cf-fi v I in,

Filed May a. 1965 ATTOR N EY United States Patent 3,277,751MOTION-COMPELLING MECHANISM FOR A HAND TOOL George J. Filia, Shelton,Conn., assignor to Sargent &

Company, New Haven, Conn., a corporation of Connecticut Filed May 6,1965, Ser. No. 453,742 Claims. (Cl. 81-313) This invention relates to amotion-compelling mecha nism for a hand tool of the type having a pairof handles so constructed and arranged with reference to one anotherthat the handles have a scissorlike action. Such tools are oftenconstructed for crimping electrical termina'ls or connectors onelectrical wires, for example.

It has been conventional practice for some years to incorporate in suchcrimpers motion-compelling means to insure that the handles of the toolmay not be moved relatively to one another in such a manner as to openthe crimper until the crimper has been closed sufficiently, once closingmovement of the crimper has begun, so that a full crimp is assumed. Itwill be appreciated that other wise the operator of the tool mightinadvertently neglect to close the crimper to the extent necessary toimpart a satisfactory physical and electrical connection between theworkpiece and the part to which it is designed to be aflixed.

Such crimpers commonly comprise a pair of cooperating jaws or dies, andit has been found helpful to employ in such a tool a motion-compellingmechanism for the foregoing reasons and which further enables the tooloperator to manipulate the handles of the tool to partially close thedies on a ferrule and then insert a Wire in the ferrule while the diesremain firmly gripping the ferrule. The motion-compelling mechanismprevents dislocation of the handles of the tool relatively to oneanother while the wire is being inserted.

Conventional motion-compelling mechanisms for tools such as describedabove by way of example have commonly employed cooperating pawl andratchet elements. It has been found that in at least some applicationsmotion-compelling mechanisms of the pawl and ratchet type have notproven entirely satisfactory in at least two aspects. Firstly, the tipof the pawl may be subject to breakage due to forces imposed on thetool. Secondly, the pawl cooperates with only one tooth of the ratchetat a time and, even while the teeth of the ratchet may be very fine, thetake-up of the pawl and ratchet mecha nism, tending to prevent openingof the tool, may not be sufficiently full once the crimping operation,for example, has commenced, to prevent undesirable effects on theworkpiece due to even a small amount of relative movement of the toolhandles in a direction to open the tool.

The invention contemplates a motion-compelling mechanism substantiallyfree of the above-mentioned faults and yet has all the advantages of amechanism of the aforementioned pawl and ratchet type, among otheradvantages, which will be apparent hereinafter.

Accordingly, it is an object of the invention to provide an improvedmotion-compelling mechanism for a hand tool.

Another object is to provide a motion-compelling mechanism for a handtool which can withstand greater forces imposed on the tool in adirection opposite that in which movement is compelled.

Still another object is to provide a motion-compelling mechanism havinga very full or fast take-up action which, therefore, has greatercompelling tendencies than commonly found in tools incorporatingconventional motioncompelling mechanisms.

A further object is to provide a motion-compelling mechanism such asdescribed above which is adjustable to compensate for rather largemanufacturing tolerances of parts of the tool such as the jaw orcrimping dies, for example, or to compensate for wear of the jaws ordies, and which motion-compelling mechanism may further incorporate astop when assembled in a tool to limit closing movement of the jaws orthe like of the tool.

For a more complete understanding of the invention, reference is made tothe following description with the accompanying drawings, in which:

FIG. 1 is a broken side elevational view, partially in section, of acrimping tool having as a part thereof a motion-compelling mechanismembodying the invention, the tool being a hand tool comprisingrelatively movable jaws which, as illustrated here, are in relativelyclosed condition;

FIG. 2 is a fragmentary view similar to FIG. 1, showing the tool withthe jaws thereof in relatively open condition;

FIG. 3 is a sectional view taken on line 33 of FIG. 2;

FIG. 4 is an enlarged fragmentary view similar to FIG. 1 illustrating insolid lines the jaws of the tool in full crimping positions just priorto engagement of the aforementioned stop, the movement of the jawstoward relatively closed condition having been fully compelled, oneelement of the motion-compelling mechanism being shown in an adjustedposition for one or both of the compensation purposes hereinbeforedescribed;

FIG. 5 is a view similar to FIG. 4 illustrating in solid lines engagedpositions which certain parts of the motioncompelling mechanism assumejust prior to the jaws reach ing the positions shown in FIG. 4, andillustrating in broken lines the positions of the aforesaid parts of themotion-compelling mechanism just prior to engagement of these partsduring initial relative movement of the jaws from their open positionsshown in FIG. 2 toward their closed positions;

FIG. 6 is a sectional view taken on line 66 of FIG. 4;

FIG. 7 is a fragmentary elevational view, partially in section,illustrating a modification of the motion-compelling mechanism;

FIG. 8 is a sectional view taken at right angles to FIG. 7; and

FIG. 9 is a sectional view taken on line 9-9 of FIG. 4.

In the form of the tool shown in FIGS. 1 through 6 and 9 there isillustrated a tool having handles 11 and 12 which may be stamped fromsheet metal and covered throughout a portion of their lengths with aplastic material as at 11 and 12 respectively, these covered portions ofthe handles constituting the arts of the tool gripped by the operator.The handles 11 and 12 in the illustrated form are of channel shape incross section, as best shown in FIG. 3, the channels being in opposingrelation to one another, and the channel of the handle 11 being enlargedas at 11 to receive a portion of the channel of handle 12, as shown inthis view, where the two handles are pivotally interconnected by a pin13 held against axial displacement by split rings 14. The pin 13 extendsthrough the side walls of both handles 11 and 12. The channel of thehandle 12 has an integrally formed raised portion 15, the purpose ofwhich will appear hereinafter.

Beyond the pivot pin 13 from the raised portion 15, as shown in FIG. 2,for example, the aforementioned handles are provided with pivot pins 16extending through the respective side walls of the handles for supportthereby and each pivotally mounting one of a pair of jaws 17 through oneend of which jaws the pin extends. The jaws 17 are pivotallyinterconnected through a pair of plates (only one being shown andindicated at 18) supporting a pair of pivots 19 therebetween, whichpivots support the respective jaws by extending therethroughintermediate their ends, the jaws being pivotally mounted in theaforesaid manner for conventional toggle-like action on swingingmovement of the aforementioned handles relatively to one another. Thejaws carry pin 17 therebetween, held captive axially by thelast-mentioned plates.

The jaws may carry as separate parts complemental crimping dies, forexample. In the form referred to above the dies 20 are shown as beingformed integrally with the respective jaws. It is to be noted, however,that the invention is not limited to a hand tool having a togglelikeaction, but may be employed in a tool having handles provided with ascissorslike action and, for example, imparting parallel movement of thejaws of the tool as illustrated and described in United States PatentNo. 3,157,075, issued November 17, 1964. The motioncompelling mechanismembodying the invention may also be incorporated in a hand tool of thetype illustrated and described in copending application, Serial No.273,407, filed April 16, 1963, now Patent No. 3,204,445, wherein thereis provided a stationary jaw, a movable jaw cooperating with thefirst-mentioned jaw, a swingable operating handle in pivoted relation tothe fixed part and pivotally interconnected to the movable jaw.

Within the channel formed by the handle 12 there is a washerlike spacer22 on the pivot pin 13, and a wire spring 23 is wound about the axis ofthe pivot pin 13 and extends over the spacer 22 for a purpose which willappear hereinafter. The ends of the spring 23 are bottomed in therespective channels of the handles 11 and 12, as shown in FIGS. 1 and 2,for example. The arrangement of the spring is such as to bias thehandles toward their open positions shown in the last-mentioned view tothereby bias the jaws to their open positions as seen in this view.

The motion compelling mechanism in which the present invention residescomprises a bracket, indicated generally at 25, pivotally supported inthe raised portion 15 of the channel of handle 12 by means of a splinedor toothed pin 26 held against angular dislocation in the side walls ofthe handle 12 through which it is extended, having complemental toothedopenings, axial movement of the pin 26 being prevented (FIG. 9) by splitrings. The bracket is slotted as at 27, and in this recess receives apinion 28 revoluble on a pin 28 suitably supported by the bracket, thepinion being in mesh with the toothed pin or gearlike element 26 so thaton rotation of the bracket 25 about the axis of the gearlike part 26,rotation is imparted to the pinion 28. A coil spring 25 disposed in thelast-mentioned channel has one end secured therein as by a pin 29 (FIG.3) extending through the side walls of the channel. The other end of thespring is secured, as at 30, to the bracket 25.

Pivotally mounted on the pivot pin 13 interconnecting the handles anddisposed within the channel of the handle 11 is a platelike part,indicated generally at 31, generally of the form of a gear sector havingrelatively fine teeth 32 extending throughout an edge portion thereoffor cooperation with the teeth of the pinion 28 which are alsorelatively fine.

At one end of the last-mentioned toothed portion the platelike part 31is provided with a camrning surface 33 on a cam nose 33 extendingradially outwardly of the pivot 13 a distance greater than the teeth 32,the lastmentioned surface being provided on an edge portion of the part31. There is provided at the other end of the last-mentioned toothedportion of the plate part 31 a recess 35 in an edge portion of theplatelike part forming a camming surface 34. The aforementioned platepart 31 may be likened to a gearlike part angularly movable on the pivot13, and for the purpose of securing the gearlike part 31 with referenceto the handle 11 there is provided an opening 36 (FIG. in the part 31through which fastening means designated generally at 37 (FIG. 6)extends, the last-mentioned fastening means extending through alignedopenings 38 formed in the side walls of with which the pinion meshes.

the handle 11. The openings 38 are elongated and angularly disposed withreference to the pivot 13, as shown, and the opening 36 in the gearlikepart 31 is also elongated and formed at a somewhat different angle withreference to the pivot 13 than the openings 38. As best shown in FIG. 6,the fastening means 37 comprises a bolt 39 having a head bearing againstthe outer face of one of the aforementioned walls of the handle 11 andhaving a cylindrical portion 40 received in the opening 38 formed in thelastmentioned wall. Beyond the cylindrical portion 40 the bolt isnarrowed or of smaller diameter, and this portion of the bolt, indicatedat 41, is threaded and extends through the other opening 38 in thelast-mentioned handle as shown in the last-mentioned view. Thecylindrical portion 40 of the bolt together with the reduced portion 41of the latter forms a shoulder against which the gearlike part abuts,and the last-mentioned part is sandwiched between the shoulder and aheaded nut 42 threaded on the portion 41 of the bolt.

It will be noted that with this construction and arrangement thegearlike part 31 may be firmly held in fixed or angularly adjustedposition with reference to the handle 11 as the handles are swungrelatively to one another on the pivot 13 in the operation of the tool.The head of the bolt 39 and the headed nut 42 may be suitably recessedas indicated in the drawings to receive a spanner wrench of a specialsize to inhibit tampering with the fastening means 37 by unauthorizedpersons.

Angular adjustment of the gearlike part 31 on the pivot 13 withreference to the handle 11 may be effected by loosening the nut 42 orbolt 39 with the aforementioned special tool and adjusting the bolt 39in the slots 38. It will be noted that during movement of thelast-mentioned bolt in the slots 38 for adjustment purposes, the boltmay have some limited movement with reference to the gearlike part 31 bymoving in the slot 36 formed in the lastmentioned part. When thefastening and adjusting means 37 is in the desired angular position withreference to the pivot 13, the bolt 39 is tightened with reference tothe headed nut 42 to firmly clamp the gearlike part 31 in adjustedposition with reference to the handle 11. As will appear more fullyhereinafter, the angular position of the gearlike part 31 with referenceto the pivot pin 13 dictates the movement of the tool handles and,therefore, the movement of the jaws and dies carried by the jaws, whichis compelled. The aforementioned spacer 22 overlaps the gearlike part31. That is, it extends beyond it in a direction to prevent bindingbetween the spring 23 and the gearlike part 31.

In the operation of the form of the tool described above, it will beunderstood with reference to the drawings that, when the tool is in theopen condition shown in FIG.

2, the tool may be held by the operator in one hand and electricalterminal or connector of the ferrule type, for example, inserted betweenthe dies 20 of the tool with the other hand of the operator. The handlesof the tool may then be manipulated in a manner to swing one relativelyto the other in a direction to effect partial closing movement of thedies to the extent that the ferrule is supported by the jaws inuncrirnped condition.

During this initial relative movement of the handles of the tool, thesurface 33 of the cam nose of the gearlike part 31 engages the pinion 28and rotates the spring-biased bracket carrying the pinion in a clockwisedirection as viewed in FIG. 2 on the axis of the gearlike element 26 Theposition which the gearlike part 31 occupies relatively to the bracket25 and its associated parts just prior to interengagement of these partsis shown in phantom in FIG. 5.

It will be understood from the foregoing that as the bracket is movedangularly on the gearlike element 26,

which is fixed to the handle 12, the pinion 28 is rotated,

the pinion being rotated in a clockwise direction, as viewed in FIG. 2.

It will also be understood from the foregoing that the spring-biasedbracket 25 is moved angularly on its aforementioned pivot only to theextent necessary to permit the cam nose of the gearlike part 31 to slippast the pinion 28. During this angular movement of the bracket, thespring 25 associated with the bracket is tensioned and, when the camnose slips past the pinion 28, the spring 25 functions to bias thebracket 25 in such manner that the teeth of the pinion 28 are quicklybrought into engagement with the teeth 32 of the gearlike part 31.

As soon as the pinion 28 is engaged with the toothed portion of the part31 in the aforesaid manner, relative opening movement of one handle ofthe tool with reference to the other handle is efficiently and verystrongly inhibited by the pinion 28, which on said movement tends towedge or jam between the gearlike element 26 and the gearlike element 31owing to the fact that the sum of the distance between the pivotal axisof the bracket 25 and the teeth of the pinion or gear 28 engaged withthe teeth 32 and the distance between the engaged teeth 32 and the axisof the pivot pin 13 is greater than the distance between the axis of thepivot 26 and the pivot 13. The wedging action of the pinion or gear 28is a very strong one, greater than the holding action of a pawl, byreason of the fact that one or more teeth of the element 28 becomemeshed with teeth 32 and one or more teeth of the element 28 also becomemeshed with teeth of the gearlike element 26 once forces are imposedupon the handles, tending to open the jaws of the tool.

Moreover, the instantaneous meshing of the teeth in the manner describedabove provides a fast or substantially complete motion take-up, therebyproviding the mechanism with a greater motion-compelling effect thanwould be obtained with the use of a pawl engaging a ratchet. It shouldbe noted here that the afore-mentioned gear teeth do not tend to mesh,that is, the teeth on the gearlike part 31 and the pinion or gearlikepart 28, unless or until there is a force exerted on the handles of thetool tending to move one handle relatively to another in a directionopposite that in which motion is compelled.

Once the teeth 32 have been engaged by the teeth of the element 28 inthe aforesaid manner, relative motion of one handle to the other and,therefore, motion of one jaw relatively to the other, is compelled and,as relative movement of the handles is continued, the teeth of thepinion or gearlike element 28 bump or rub relatively over the teeth 32of the gearlike element 31, the frictional contact between the teethbeing dependent on the strength of the spring 25 biasing the bracket 25as the pinion moves to the full-line position shown in FIG. 5. Inconnection with the aforementioned rubbing action of the teeth of thegearlike element 28 relatively to the teeth 32 of the element 31, itshould be noted that the teeth of the elements 28 and 31 are preferablyrounded.

As closing movement of the handles is continued, the pinion 28 leavesthe teeth 32 and the pinion is released from the gear-like part 31 whenit enters the recess 35 formed in the last-mentioned part, the tensionspring 25 tending to facilitate the aforementioned release of the pinionor snap the bracket carrying the pinion to the released position inwhich the pinion extends into the aforementioned recess. At this pointin the movement of the jaws effected through movement of the handles ofthe tool, the electrical terminal or connector is fully crimped andmovement of one handle relatively to the other in a closing directionmay be continued only until the bracket strikes the edge portion 35 ofthe recess 35 in the part 3-1, at which point further relative closingmovement of the handles is prevented to inhibit damage to the connector.

It will be understood from the foregoing that, when the pinion orgearlike part 28 disengages the gearlike part 31, the handles of thetool may move relatively to one another in a direction to open the jawsof the tool. On initial opening movement of the handles, the cam surface34 provided by the recess 35 in the part 31 engages the pinion 28 andimparts an angular movement to the bracket 25 in a counterclockwisedirection to move the pinion over center of an imaginary line betweenthe axes of the pivot pin 13 and the pivot 26, as viewed in FIG. 4. Theteeth of the pinion engage the teeth of the gearlike part 31. Once theteeth are so engaged, the handles of the tool may not be movedrelatively to one another to effect closing movement of the die-carryingjaws. When the pinion 28 leaves the teeth 32 of the part 31, theaforesaid cam nose of the part 31 engages successive teeth of the pinion28 and rubs relatively over them against the action of the tensionspring influencing the pivotal bracket 25. As soon as the cam nose ofthe part 31 slips relatively past the pinion 28, the motion-compellingmech-a nism is released and here again the action of the springassociated with the bracket 25 serves to snap the bracket in an angulardirection to facilitate release of the mechanism.

When the teeth are engaged as the handles move relatively to one anotherto open the jaws, the motion-compelling mechanism may only be releasedby a force such as from a finger of the operator on the tang 25 of thebracket 25, tending to swing the bracket counterclockwise as viewed inFIG. 5. It will also be understood that, When the teeth of the gearlikepart 28 are engaged with the teeth of the gearlike part 31 as thedie-equipped jaws move toward their closed positions, themotion-compelling mechanism may only be released by the operator by athrust on the tang 25 as aforesaid but in a direction to impart aclockwise angular movement to the bracket 25.

In the modified form of the invention shown in FIGS. 7 and 8 of thedrawings, the bolt indicated generally at 45, somewhat similar to thebolt 39, has a toothed portion 46 corresponding to the portion 40 of thebolt 39 and extending through one side wall 47 of a handle similar tothe above-described handle 11. The toothed portion 46 extends through anopening 48 formed in the wall 47. A portion of the means defining theopening 48 defines serrations or teeth 49 extending into the opening forthe purpose of meshing with the teeth of the toothed portion 46 of thebolt so that, when the bolt is loosened for adjustment in the opening 48in a manner similar to the above-described loosening of the bolt 39 foradjustment purposes, the bolt 45 may be adjusted by turning in theopening 48 which is elongated, in desired increments. Such aconstruction and arrangement may be incorporated in themotion-compelling mechanism of the invention for applications in whichit is desired to have the securing means for the gearlike part 31adjustable within finer limits than is practical in the first-describedform, and this construction provides a greater holding action be tweenthe handle and the bolt. The bolt 45 secures the gearlike part 31 infixed adjusted position with reference to the corresponding handle ofthe tool in the same manner in which the bolt 39 secures the gearlikepart 31 in place.

While only two forms of the invention have been illustrated in thedrawings and described above, it will be appreciated by those versed inthe art that the invention may take other forms and is susceptible ofvarious changes in details without departing from the principles of theinvention and the scope of the appended claims.

What is claimed is:

1. In a tool having first and second handles pivotally interconnectedand adapted for the support of and respective association withwork-performing elements of a pair, which cooperate With one another onrelative swing ing movement of the handles with respect to each other,the combination comprising a first toothed element having teeth arrangedon a radius and secured to the first handle for relative swingingmovement therewith in angularly rigid relation thereto, a second toothedelement having teeth arranged on a radius and secured to the secondhandle for relative swinging movement therewith in angularly rigidrelation thereto, and a gearlike part supported from one of said handlesfor swinging movement therewith and for angular movement on its axis,said gearlike part also being supported from said one of the handles forswinging movement on an axis coincident with the point from which theteeth of the corresponding toothed element associated with thelast-mentioned handle are generated on a radius as aforesaid, saidgearlike part being spring biased toward the other toothed element, theteeth of the gearlike part being engageable with the teeth of saidtoothed elements simultaneously during relative swinging movement of thehandles one to the other in either direction to compel rela tivemovement of the handles in this direction While said teeth are soengaged.

2. A tool as definedin claim 1 wherein said gearlike part comprises apinion and the support for the gearlike part from the handle whichpermits swinging movement on an eccentric axis and relatively to thehandle with .which the gearlike part is associated comprises a bracketswingably supported on the toothed element associated with thelast-mentioned handle.

3. A tool as defined in claim 1 wherein the toothed element associatedwith said one of the handles is constituted by a splined or toothed pin,the other toothed element being generally of the form of a gear sector,and said gear-like element comprising a pinion.

4. A tool as defined in claim 1 wherein the support for the toothedelement on the other handle is angularly adjustable with respect to saidpivotal connection of the handles to vary the degree of motion which iscompelled by said gearlike part.

5. A tool as defined in claim 2 wherein said bracket coacts with a partcarried by the other handle to provide a stop for limiting relativeswinging movement of the handles in one direction.

6. A tool as defined in claim 2 wherein the toothed element associatedwith the other handle is provided with a cam nose at one end of itsteeth to engage the pinion and swing the bracket carrying the pinion inone direction against said bias, the last-named toothed part alsocomprising means defining a recess bounded in part by a cam surface toengage and swing the bracket in the other direction against said bias.

7. A tool as defined in claim 5 wherein said bracket is provided with atang manipulatable by the operator of the tool to disengage saidgearlike part from the other toothed element after the teeth have becomeengaged in the aforesaid manner to release the motion-compellinggearlike part.

8. A tool as defined in claim 5 wherein said adjustment means comprisesmeans defining a slot in said other handle and a bolt infinitelyadjustable within the limits of said slot and extending through anaperturein the last-mentioned toothed element.

9. A tool as defined in claim 5 wherein said adjustment means comprisesmeans defining a slot having teeth therein in said other handle and abolt having a toothed portion cooperating with the last-mentioned teethfor adjustment in the slot and extending through an aperture in thelastmentioned toothed element.

10. In a tool having first and second handles pivotally interconnectedand adapted for the support of and respective association withwork-performing elements of a pair, which cooperate with one another onrelative swinging movement of the handles with respect to each other,the combination comprising a pinionlike element angularly fixed to thefirst handle, a gearlike element secured to the second handle forrelative swinging movement therewith in angularly rigid relationthereto, a bracket swingable on the pinionlike element, a pinion carriedby the bracket eccentrically of its swinging axis and supported by thebracket for angular movement, the bracket being spring biased towardsaid gearlike element, the teeth of the pinion carried by the bracketbeing engageable with the teeth of said pinionlike element and the teethof the gearlike element simultaneously during relative swinging movementof the handles one to the other in either direction to compel relativemovement of the handles in this direction While said teeth are soengaged, said bracket coacting with means defined on said ,gearlike partto provide a stop for limiting relative swinging movement of the handlesin one direction.

References Cited by the Examiner UNITED STATES PATENTS 1,897,511 2/1933Taylor 8l9.1 2,868,048 1/1959 Pachter 81-9.l 3,157,075 11/1964 Filia81-313 WILLIAM FELDMAN, Primary Examiner.

M. S. MEHR, Assistant Examiner.

1. IN A TOOL HAVING FIRST AND SECOND HANDLES PIVOTALLY INTERCONNECTEDAND ADAPTED FOR THE SUPPORT OF AND RESPECTIVE ASSOCIATION WITHWORK-PERFORMING ELEMENTS OF A PAIR, WHICH COOPERATIVE WITH ONE ANOTHERONE RELATIVE SWINGING MOVEMENT OF THE HANDLES WITH RESPECT TO EACHOTHER, THE COMBINATION COMPRISING A FIRST TOOTHED ELEMENT HAVING TEETHARRANGED ON A RADIUS AND SECURED TO THE FIRST HANDLE FOR RELATIVESWINGING MOVEMENT THEREWITH IN ANGULARLY RIGID RELATION THERETO, ASECOND TOOTHED ELEMENT HAVING TEETH ARRANGED ON A RADIUS AND SECURED TOTHE SECOND HANDLE FOR RELATIVE SWINGING MOVEMENT THEREWITH IN ANGULARLYRIGID RELATION THERETO, AND A GEARLIKE PART SUPPORTED FROM ONE OF SAIDHANDLES FOR SWINGING MOVEMENT THEREWITH AND FOR ANGULAR MOVEMENT ON ITSAXIS, SAID GEARLIKE PART ALSO BEING SUPPORTED FROM SAID ONE OF THEHANDLES FOR SWINGING MOVEMENT ON AN AXIS COINCIDENT WITH THE POINT FROMWHICH THE TEETH OF THE CORRESPONDING TOOTHED ELEMENT ASSOCIATED WITH THELAST-MENTIONED HANDLE ARE GENERATED ON A RADIUS AS AFORESAID, SAIDGEARLIKE PART BEING SPRING BIASED TOWARD THE OTHER TOOTHED ELEMENT, THETEETH OF THE GEARLIKE PART BEING ENGAGEABLE WITH THE TEETH OF SAIDTOOTHED ELEMENTS SIMULTANEOUSLY DURING RELATIVE SWINGING MOVEMENT OF THEHANDLES ONE TO THE OTHER IN EITHER DIRECTION TO COMPEL RELATIVE MOVEMENTOF THE HANDLES IN THIS DIRECTION WHILE SAID TEETH ARE SO ENGAGED.